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• Why do I need to compile ffmpeg only directly on PC on which I will develop application which will use ffmpeg libraries ?

  21 janvier 2015, par bukka.wh

  I am going to develop an application which will use ffmpeg library on my PC under Windows 8 on it. I am also going to develop my program with using Visual Studio. I have read here that to use ffmpeg as a library in my project I need compile ffmpeg at first.

  The compilation ffmpeg on OS Windows is really not very easy. And I want to know why it is impossible to compile ffmpeg on Windows at once and then use this build on any computer running OS Windows ? Why we cant do this ?
  May be someone can give me all that *.lib files that were created after compiling ffmpeg on Windows ?

• Writing Live-Multimedia-Application using OpenGL & Co. saving output to disc [closed]

  21 janvier 2013, par user1997286

  I want to write an application that does the following thing :

  • Getting Commands via ArtNET (DMX over Ethernet, a Control Protocol) for each object (called Layer)
  • each Layer could be one of the following : Live Camera Stream, Movie, Image
  • each layer could be translated, rotated or stretched
  • on each layer I can set filters (Like a Kaleidoscope Effect, Blur, Color Correction, etc.)
  • the rsulting video-stream is in the 3d-space
  • I want to display each part of the image on one Projector (in total up to 3 ones) using a TripleHead2GO (3 Projectors display a different region of my DVI-Output). Each Projecector-Image should have own Soft-Edge and Keystone parameters.
  • the resulting image will also be shown on a Preview-Screen with some Information overlay.

  I think all that should be possible with opengl and openal (for the movie audio)

  I think I'll use C++, OpenGL for Graphics, OpenAL for Audio, if needed ffmpeg for Video conversion, Ubuntu/Debian as OS.

  The software is used to do Multimedia-Shows on Concerts including Cameras & Co.

  All that should happen Live (On a FullHD output), Having i7 3770, GLX 670 and 16GB of Ram for at least 8 Layers. (4 Live-Images at once + Some Overlays like the Actors Name and some Logos)

  But now comes the question.

  Is it also Posible to do the following with that setting :

  • Writing the output Image with all the 3d translations to a Movie File (To Master a DVD later) with Audio
  • Mixing Audio from different Inputs & Files (Ambience Mics, Signal from the Sound Mixer, Playbacks from my own application) to more than one Mix (eg. one Mix for the Recording, one Mix for Live)
  • Stream that Output Complete or in Parts (e.g. the left Part of the Image) over the Network (For example, Projector 1 is near the Server, so I connect it using DVI, Projector 2+3 is connected to a Computer that receives the streams for that two projectors (with soft edge on each stream) and Screen 4 is outside the Concert Hall and shows the complete Live-Stream.
  • What GUI-Framework should I use for that ?
  • is it perhaps event performant enough to use Java for that ?
  • is it posible to use that mechanism for just rendering (eg. I have stored the cut points on Disc and saved every single camera stream to change some errors later or cut out some parts)

• application using ffmpeg segfaults because of for loop ?

  6 décembre 2012, par larvyde

  I am writing my first ffmpeg application using the tutorial linked to from the ffmpeg.org documentation page [tutorial] [sample]. Here is my initial code :

  const char * fnmVideoIn = argv [1];
  
  const char * fnmImageOut = argv [2];
  
  
  
  av_register_all ();
  
  
  
  // [] Open the file
  
  AVFormatContext * pcxFormat;
  
  if (avformat_open_input (&pcxFormat, fnmVideoIn, NULL, NULL)) {
  
      fprintf (stderr, "Could not open file %s for reading\n",
  
              fnmVideoIn);
  
      return -1;
  
  }
  
  
  
  // [] Get stream information
  
  if (avformat_find_stream_info (pcxFormat, NULL) < 0) {
  
      fprintf (stderr, "Could not find stream info\n");
  
      return -1;
  
  }
  
  
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);

  and all is well. The program runs without errors and dumps the video info properly. but then I got to the next step...

  ...
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);
  
  
  
  int ixVideoStream = -1, ixStrm;
  
  for (ixStrm = 0; ixStrm < pcxFormat->nb_streams; ++ixStrm) {
  
      if (pcxFormat->streams [ixStrm]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          ixVideoStream = ixStrm;
  
          break;
  
      }
  
  }

  and it exits with a segfault. gdb says :

  (gdb) r test.mp4 out
  
  ...
  
  Program received signal SIGSEGV, Segmentation fault.
  
  0xb7f572c5 in avformat_open_input () from /usr/lib/libavformat.so.53

  how is it possible that avformat_open_input segfaults because of code added after it is called ? I even tested it with a regular i=0 ; i<100 for-loop and it still segfaults ! is this a bug ? For reference, my system is :

  $ gcc --version
  
  gcc (GCC) 4.7.0 20120414 (prerelease)
  
  
  
  $ uname -srvmpio
  
  Linux 3.3.4-1-ARCH #1 SMP PREEMPT Sat Apr 28 06:04:27 UTC 2012 i686 Intel(R) Core(TM)2 Duo CPU P7450 @ 2.13GHz GenuineIntel GNU/Linux
  
  
  
  $ ffmpeg -version
  
  ffmpeg version 0.10.2
  
  built on Mar 17 2012 08:53:01 with gcc 4.6.3
  
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-libgsm --enable-libspeex --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-libpulse --enable-gpl --enable-version3 --enable-runtime-cpudetect --disable-debug --disable-static
  
  libavutil      51. 35.100 / 51. 35.100
  
  libavcodec     53. 61.100 / 53. 61.100
  
  libavformat    53. 32.100 / 53. 32.100
  
  libavdevice    53.  4.100 / 53.  4.100
  
  libavfilter     2. 61.100 /  2. 61.100
  
  libswscale      2.  1.100 /  2.  1.100
  
  libswresample   0.  6.100 /  0.  6.100
  
  libpostproc    52.  0.100 / 52.  0.100